Response of wheat and barley varieties
to phosphorus fertilizer, 2010
M. J. Ottman
Summary
Phosphorus fertilizer represents a significant portion of the cost of producing small grains. Some evidence exists
that there are differences in the ability of small grain varieties to take phosphorus up from the soil and utilize this
nutrient in the grain. The objective of this study is to determine if barley and wheat varieties grown in Arizona
differ in their response to phosphorus fertilizer. A study was conducted for the second year at the Maricopa
Agricultural Center testing the response of 7 barley and 14 wheat (12 durum wheat and 2 bread wheat) varieties to
2 phosphorus rates (0 and 100 lbs P2O5/acre). The grain yield increase due to phosphorus application averaged
across varieties in 2010 was 170 lbs/acre for barley (not statistically significant) and 545 lbs/acre for wheat. The
grain yield increase averaged across varieties and years was 331 lbs/acre for barley and 577 lbs/acre for wheat.
The barley and wheat varieties did not differ in their grain yield increase due to phosphorus fertilizer in 2010.
However, based on 2 years of results, we were able to detect differences among wheat but not barley varieties in
their response to P fertilizer. The yield response to P fertilizer (100 lbs P2O5/acre) among durum wheat varieties
varied from 331 lbs/acre for Alamo to 1063 lbs/acre for Orita. Yecora rojo, a bread wheat, did not respond to P
fertilizer.
Introduction
Phosphorus fertilizer costs have increased dramatically in the past few years. In small grain production, fertilizer
represents a significant proportion of the cost of production. The availability of soil P can be influenced by root
exudates, which are under genetic control (Rengel, 2002). Small grain varieties may differ in their response to
phosphorus fertilizer due to the presence or absence of these exudates or other factors (Davies et al., 2002). Citric
acid is one of the root exudates that have been identified and related to phosphorus availability. The objective of
this study is to determine if wheat and barley varieties grown in Arizona differ in their response to phosphorus
fertilizer. This is the second year of the study.
Procedure
A study was conducted at the University of Arizona Maricopa Agricultural Center to determine if wheat and barley
varieties respond to phosphorus fertilizer differently. The soil type was a Casa Grande sandy loam with a preplant
soil phosphate level of 2.0 ppm P. P fertilizer treatments were applied before planting at rates of 0 and 100 lbs
P2O5/acre using triple super phosphate (0-45-0) as a fertilizer source. The P fertilizer was applied by hand to plots 5
ft x 20 ft in size. The seed was planted with a cone planter in seven rows spaced 7 inches apart and 20 ft long. The
seeding rate was approximately 100 lbs/acre for durum varieties and 85 lbs/acre for barley varieties. The
experimental design of the P x Variety Study was a split plot with varieties (7 barley and 14 wheat [12 durum wheat
and 2 bread wheats]) as main plots and P rate (0 and 100 lbs P2O5/acre) as subplots, and replicated 6 times. A P
Rate Study with a wider range of P rates (0, 25, 50, 75, 100, 150 and 200 lbs P2O5/acre) and a single variety (Gustoe
barley and Kronos durum) was also conducted to determine if the P rate of 100 lbs P2O5/acre is adequate for
optimum yield. Cultural practices are listed in Table 1. The following data was collected: grain yield, test weight,
plant height, lodging, heading, flowering, physiological maturity, grain P, grain protein, HVAC, and light
interception on Feb 12 at the 5 leaf stage. Grain was harvested with a small plot combine and yields are expressed
on an “as is” moisture basis. HVAC was determined from 10 g of seed. Grain protein was calculated using the
combustion method to obtain total N, which was multiplied by 6.25 (barley) or 5.7 (wheat) to obtain protein content
and expressed on a 12% moisture basis. Flowering is defined as when about half of the heads are shedding pollen
and physiological maturity is defined as when the glumes turn brown. Light interception was determined by
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
56
dividing the average of six readings from a sunfleck ceptometer at ground level by incident light level.
Abbreviations for the sources of varieties are: APB = Arizona Plant Breeders, WPB = Western Plant Breeders,
WWW = World Wide Wheat, UC = University of California.
Results and Discussion
This growing season was characterized by below average temperature and above average rainfall (Table 2).
Temperatures were especially cool during the months of March, April, and May. The month of January was
especially wet. Due to the cool weather, the growing season was extended by 1-2 weeks compared to normal.
P rate study (6 P rates and 1 barley and 1 wheat variety):
Grain yields of Gustoe barley were not affected by phosphorus rates from 0 to 200 lbs P2O5/acre, whereas grain
yield of Kronos durum increased linearly with P rate (Table 3). P rate also decreased time to heading; increased
grain P content; and increased light interception measured on Feb 12.
P x variety study (2 P rates and 7 barley and 14 wheat varieties)
We measured a P rate response to many variables (Tables 4-6). P rate increased yield (wheat), test weight (wheat),
plant height (barley), decreased time to heading and maturity, increased light interception as measured on Feb 12,
and increased grain phosphorus concentration.
The varieties responded to an application of 100 lbs P2O5/acre in a similar manner for all of the variables measured
(Tables 4-6).
The results from 2010 do not provide any evidence that barley and wheat varieties respond differently to P fertilizer.
However, if the results from 2009 and 2010 are combined, we were able to detect differences among wheat but not
barley varieties in their response to P fertilizer. The yield response to P fertilizer (100 lbs P 2O5/acre) among durum
wheat varieties varied from 331 lbs/acre for Alamo to 1063 lbs/acre for Orita. Yecora rojo, a bread wheat, did not
respond to P fertilizer.
Acknowledgments
Financial support for this project was received from the Arizona Grain Research and Promotion Council and the
Arizona Crop Improvement Association. The technical assistance of Mary Comeau and Mike Sheedy is greatly
appreciated.
References
Davies, T.G.E., J. Ying, Q. Xu, Z.S. Li, J. Li, and R. Gordon-Weeks. 2002. Expression analysis of putative highaffinity phosphate transporters in Chinese winter wheats. Plant, Cell and Environment. 25:1325-1339.
Rengel, Z. 2002. Genetic control of root exudation. Plant and Soil 245:59-70.
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
57
Table 1. Cultural practices for the small grain phosphorus trial at Maricopa.
Cultural
information
Maricopa
Previous crop
Fallow
Soil texture
Sandy clay loam
Planting date
12/10/09
Irrigations
6
12/10, 12/21, 2/17, 3/17, 4/1, 4/15, 5/1
Nitrogen (lbs N/a)
220
12/12: 51 (46-0-0)
1/28: 24 (32-0-0)
2/25: 76 (32-0-0)
3/13: 74 (32-0-0)
Phosphorus
(lbs P2O5/acre)
100
Pesticides
None
Harvest date
6/1 (Durum)
6/3 (Barley)
Table 2. Climatic data from AZMET for Maricopa during the 2010 growing season compared to the long-term
average.
Climate
variable
Unit
Year(s)
Dec
Jan
Feb
Mar
Apr
May
Dec-May
Max
Temp.
ºF
ºF
2010
Avg
64
65
66
66
68
70
73
77
82
85
90
95
74
76
Min
Temp.
ºF
ºF
2010
Avg
33
35
38
36
41
39
43
44
49
51
55
60
43
44
Ppt.
inches
inches
2010
Avg
0.39
0.62
2.64
0.72
0.56
0.85
0.62
0.79
0.00
0.26
0.00
0.20
4.21
3.43
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
58
Table 3. Phosphorus rate effect on grain yield and other plant characteristics for ‘Gustoe’ barley and ‘Kronos’
durum.
Grain
Phosphorus
%
Grain
Protein
%
HVAC
%
Light
interception
(Feb 12)
%
P rate
lbs/A
Yield
lbs/A
Test
Weight
lbs/bu
Plant
Height
inches
0
25
50
75
100
150
200
Avg
5704
6438
6552
6130
5653
5623
5731
5976
50.3
50.2
49.5
50.1
49.9
50.3
50.5
50.1
34.3
33.5
33.8
34.3
35.3
33.5
33.8
34.0
4/04
4/01
3/30
3/31
3/31
3/31
3/31
3/31
Barley
-----------------
5/15
5/14
5/11
5/13
5/12
5/12
5/12
5/13
0.219
0.224
0.230
0.245
0.247
0.258
0.280
0.243
11.6
11.9
11.8
11.6
11.7
11.4
11.7
11.7
-----------------
61
84
81
90
86
87
84
82
P rate
Linear
Quad
Cubic
NS
NS
NS
NS
NS
NS
+
NS
NS
NS
NS
NS
**
**
**
*
---------
NS
NS
NS
NS
**
**
NS
NS
NS
NS
NS
*
---------
**
**
**
+
0
25
50
75
100
150
200
Avg
6913
7353
7519
7474
7895
7186
8246
7512
62.0
62.3
62.3
62.5
62.6
62.5
62.5
62.4
36.0
36.5
36.5
35.5
36.3
35.8
35.3
36.0
3/24
3/22
3/22
3/22
3/22
3/22
3/22
3/22
Durum
.
3/26
3/26
3/26
3/26
3/26
3/26
3/26
5/15
5/15
5/15
5/14
5/13
5/14
5/15
5/14
0.244
0.250
0.251
0.276
0.263
0.273
0.298
0.265
14.5
14.5
14.5
14.8
14.7
14.6
14.7
14.6
100
100
100
100
100
100
100
100
49
68
68
73
75
76
72
69
P rate
Linear
Quad
Cubic
*
*
NS
*
NS
NS
NS
NS
NS
NS
NS
NS
**
**
**
**
NS
NS
NS
NS
NS
NS
NS
NS
**
**
NS
NS
NS
NS
NS
NS
NS
NS
NS
+
**
**
**
NS
Heading Flowering Maturity
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
59
Table 4. Grain yield, test weight, and plant height of barley and wheat varieties as affected by phosphorus fertilizer
rates of 0 and 100 lbs P2O5/acre. “Response” refers to the difference between the phosphorus rates. The wheat
varieties are durums except for Yecora Rojo and Joaquin, which are bread wheats.
Grain Yield
Entry
Source
Chico
Cochise
Gustoe
Nebula
Commander
Max
Baretta
Avg
WPB
WPB
WPB
WPB
WWW
WWW
APB
---
LSD.05*
Entry
P rate
Entry x P
Alamo
Havasu
Orita
WPB-881
Crown
Duraking
Q-Max
Kronos
Sky
Ocotillo
Westmore
Maestrale
Yecora Rojo
Joaquin
Avg
LSD.05*
Entry
P rate
Entry x P
WPB
WPB
WPB
WPB
WWW
WWW
WWW
APB
APB
APB
APB
Allstar
Public
WPB
---
Test Weight
Plant Height
Phosphorus
0 lb/A 100 lb/A Response 0 lb/A 100 lb/A Response 0 lb/A 100 lb/A Response
lbs/A
lbs/bu
inches
5802
4906
6798
6492
6662
6035
7200
6258
5840
5127
6739
6929
7160
5992
6989
6397
39
220
268
438
498
-43
-211
170
49.7
50.7
50.1
51.0
49.6
49.8
50.4
50.2
781
**
NS
NS
781
NS
0.7
**
NS
+
6573
7166
6567
6797
5558
6619
4708
6660
7510
6402
7143
6004
7100
7367
6581
6492
7989
7693
7123
6351
7389
5399
7442
8028
6922
7479
6711
6824
8106
7139
-81
823
999
355
793
770
692
782
518
520
336
707
-276
739
545
64.1
63.8
60.2
62.0
57.6
62.2
58.3
61.7
61.2
62.3
62.7
63.3
63.9
63.5
61.9
735
**
**
NS
735
NS
0.9
**
**
NS
Barley
50.3
51.2
49.9
50.8
49.6
49.4
51.2
50.3
0.6
0.6
-0.2
-0.2
0.0
-0.4
0.8
0.2
31.7
34.8
34.0
37.0
33.8
34.0
34.2
34.2
31.8
36.0
34.5
37.0
35.2
34.8
35.2
34.9
0.2
1.2
0.5
0.0
1.3
0.8
1.0
0.7
0.7
0.8
1.4
**
**
NS
1.4
NS
Wheat
64.1
64.5
61.3
62.1
59.1
62.2
59.2
61.9
61.6
62.4
63.2
63.5
63.4
63.5
62.3
0.0
0.7
1.1
0.1
1.5
0.0
0.9
0.2
0.3
0.1
0.5
0.2
-0.6
0.0
0.4
36.5
36.2
36.0
37.2
37.8
35.7
37.8
36.7
34.7
37.8
36.0
37.5
33.3
36.7
36.4
36.5
37.0
36.5
36.7
38.0
36.3
37.7
36.2
34.0
38.3
36.3
37.7
34.7
36.8
36.6
0.0
0.8
0.5
-0.5
0.2
0.7
-0.2
-0.5
-0.7
0.5
0.3
0.2
1.3
0.2
0.2
0.9
NS
1.1
**
NS
NS
1.1
NS
* LSD.05 = least significant difference between means within a column with a 5% or less probability the difference is
due to chance.
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
60
Table 5. Heading, physiological maturity, and light interception of barley and wheat varieties as affected by
phosphorus fertilizer rates of 0 and 100 lbs P 2O5/acre. “Response” refers to the difference between the phosphorus
rates. The wheat varieties are durums except for Yecora Rojo and Joaquin, which are bread wheats.
Heading
Entry
Source
Chico
Cochise
Gustoe
Nebula
Commander
Max
Baretta
Avg
WPB
WPB
WPB
WPB
WWW
WWW
APB
---
LSD.05*
Entry
P rate
Entry x P
Alamo
Havasu
Orita
WPB-881
Crown
Duraking
Q-Max
Kronos
Sky
Ocotillo
Westmore
Maestrale
Yecora Rojo
Joaquin
Avg
LSD.05*
Entry
P rate
Entry x P
WPB
WPB
WPB
WPB
WWW
WWW
WWW
APB
APB
APB
APB
Allstar
Public
WPB
---
Physiological Maturity
Light Interception (Feb 12)
Phosphorus
0 lb/A 100 lb/A Response 0 lb/A 100 lb/A Response 0 lb/A 100 lb/A Response
% of incident
3/28
3/15
3/31
3/27
3/30
4/01
3/27
3/27
3/25
3/15
3/29
3/23
3/28
3/28
3/25
3/25
-3
0
-2
-4
-2
-2
-3
-2
5/14
5/03
5/14
5/13
5/13
5/17
5/11
5/12
2
**
**
NS
2
2
4
**
**
NS
3/25
3/24
3/29
3/26
3/30
3/30
4/03
3/25
3/25
3/25
3/24
3/27
3/23
3/22
3/26
3/22
3/22
3/27
3/22
3/27
3/25
3/28
3/22
3/22
3/23
3/22
3/24
3/22
3/21
3/23
-3
-3
-3
-4
-3
-4
-6
-3
-3
-3
-2
-3
-2
-2
-3
5/18
5/15
5/17
5/15
5/19
5/17
5/21
5/15
5/18
5/14
5/14
5/14
5/14
5/16
5/16
1
**
**
NS
1
NS
2
**
**
**
Barley
5/11
5/02
5/12
5/06
5/13
5/13
5/07
5/09
-4
-1
-2
-7
1
-3
-4
-3
48
60
72
56
60
62
58
59
64
80
80
82
79
77
77
77
17
20
8
26
19
15
19
18
4
NS
15
*
**
NS
15
NS
Wheat
5/18
5/14
5/16
5/15
5/16
5/17
5/18
5/15
5/17
5/15
5/13
5/13
5/08
5/15
5/15
0
0
-1
0
-3
-1
-3
0
-1
1
-1
0
-5
-1
-1
62
44
49
68
41
33
25
44
51
53
58
51
56
60
50
62
69
69
70
52
45
26
65
72
67
65
66
72
58
61
1
25
20
2
11
12
0
21
22
14
7
15
16
-1
12
2
3
17
**
**
NS
17
18
* LSD.05 = least significant difference between means within a column with a 5% or less probability the difference is
due to chance.
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
61
Table 6. Grain phosphorus, grain protein, and percentage of kernels “hard and vitreous and of amber color”
(HVAC) of barley and wheat varieties as affected by phosphorus fertilizer rates of 0 and 100 lbs P 2O5/acre.
“Response” refers to the difference between the phosphorus rates. The wheat varieties are durums except for
Yecora Rojo and Joaquin, which are bread wheats.
Grain Phosphorus
Entry
Source
Chico
Cochise
Gustoe
Nebula
Commander
Max
Baretta
Avg
WPB
WPB
WPB
WPB
WWW
WWW
APB
---
LSD.05*
Entry
P rate
Entry x P
Alamo
Havasu
Orita
WPB-881
Crown
Duraking
Q-Max
Kronos
Sky
Ocotillo
Westmore
Maestrale
Yecora Rojo
Joaquin
Avg
LSD.05*
Entry
P rate
Entry x P
WPB
WPB
WPB
WPB
WWW
WWW
WWW
APB
APB
APB
APB
Allstar
Public
WPB
---
Grain Protein
Phosphorus
0 lb/A 100 lb/A Response 0 lb/A 100 lb/A Response 0 lb/A
%
%
0.24
0.26
0.22
0.25
0.24
0.22
0.25
0.24
0.27
0.28
0.25
0.26
0.26
0.27
0.27
0.27
0.03
0.02
0.03
0.02
0.02
0.05
0.02
0.03
12.2
11.8
11.9
12.4
12.4
12.8
13.2
12.4
NS
NS
**
NS
NS
NS
0.8
*
+
NS
0.30
0.27
0.29
0.27
0.29
0.28
0.28
0.28
0.27
0.30
0.27
0.27
0.28
0.27
0.28
0.30
0.31
0.30
0.31
0.31
0.29
0.30
0.30
0.30
0.31
0.30
0.29
0.30
0.30
0.30
0.01
0.04
0.01
0.04
0.02
0.01
0.02
0.02
0.03
0.01
0.03
0.02
0.03
0.02
0.02
15.1
14.8
15.7
14.5
15.6
14.7
15.7
14.8
14.0
15.0
15.8
14.6
14.7
14.6
15.0
NS
NS
**
NS
NS
NS
0.7
**
NS
NS
HVAC
100 lb/A Response
%
Barley
11.9
11.4
12.1
12.2
12.3
12.7
12.2
12.1
-0.3
-0.4
0.1
-0.2
-0.1
-0.1
-1.0
-0.3
-----------------
-----------------
-----------------
0.8
NS
---------
---
---
Wheat
15.1
14.6
15.6
14.5
15.4
14.6
14.9
15.0
14.0
14.9
16.6
14.3
15.1
14.9
15.0
0.0
-0.2
-0.1
0.0
-0.2
-0.1
-0.8
0.2
0.0
-0.1
0.9
-0.3
0.4
0.4
0.0
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.7
NS
--*
NS
NS
---
NS
* LSD.05 = least significant difference between means within a column with a 5% or less probability the difference is
due to chance.
2010 Forage & Grain Report, College of Agriculture and Life Sciences, University of Arizona
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